"You'll need a new app to open this file" is probably the most common error faced by millions of Windows users every day. This is either because the program required to open a file is not available on your system or there may be other issues.

What is .PAB file extension?

Address book file used by Microsoft e-mail programs; contains information for personal and organizational contacts; stored separately from other Outlook data.
The following instructions may be used to identify the PAB file used by your email profile:
Open Microsoft Outlook.
From the Tools menu, select "E-mail Accounts."
Under the Directory tab, click "View or change existing directories or address books," and then click Next.
Under "You can choose a directory or address book below to change or remove it," first click Personal Address Book, then click Change.
Note the path of your PAB file that is in the Path box. This is where your personal address book file is located.
Click OK, then click Finish to close all open dialog boxes.
In contrast to Outlook Address Books (.OAB files), Outlook stores PAB address book files separately from your email messages. PAB files may be added to your email profile, and users can manually add additional address book information to them.
You can see a list of software programs here on easyfileopener.org that can open this file type so that you don’t need to search for it on the web. You can then open your file with this extension using a software listed below.